xref: /freebsd/sys/compat/linux/linux_util.c (revision 74bf4e164ba5851606a27d4feff27717452583e5)
1 /*
2  * Copyright (c) 1994 Christos Zoulas
3  * Copyright (c) 1995 Frank van der Linden
4  * Copyright (c) 1995 Scott Bartram
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the author may not be used to endorse or promote products
16  *    derived from this software without specific prior written permission
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  *
29  *	from: svr4_util.c,v 1.5 1995/01/22 23:44:50 christos Exp
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include <sys/param.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 #include <sys/namei.h>
40 #include <sys/proc.h>
41 #include <sys/systm.h>
42 #include <sys/vnode.h>
43 
44 #include <machine/stdarg.h>
45 
46 #include <compat/linux/linux_util.h>
47 
48 const char      linux_emul_path[] = "/compat/linux";
49 
50 /*
51  * Search an alternate path before passing pathname arguments on
52  * to system calls. Useful for keeping a separate 'emulation tree'.
53  *
54  * If cflag is set, we check if an attempt can be made to create
55  * the named file, i.e. we check if the directory it should
56  * be in exists.
57  */
58 int
59 linux_emul_find(td, sgp, path, pbuf, cflag)
60 	struct thread	 *td;
61 	caddr_t		 *sgp;		/* Pointer to stackgap memory */
62 	char		 *path;
63 	char		**pbuf;
64 	int		  cflag;
65 {
66 	char *newpath;
67 	size_t sz;
68 	int error;
69 
70 	error = linux_emul_convpath(td, path, (sgp == NULL) ? UIO_SYSSPACE :
71 	    UIO_USERSPACE, &newpath, cflag);
72 	if (newpath == NULL)
73 		return (error);
74 
75 	if (sgp == NULL) {
76 		*pbuf = newpath;
77 		return (error);
78 	}
79 
80 	sz = strlen(newpath);
81 	*pbuf = stackgap_alloc(sgp, sz + 1);
82 	if (*pbuf != NULL)
83 		error = copyout(newpath, *pbuf, sz + 1);
84 	else
85 		error = ENAMETOOLONG;
86 	free(newpath, M_TEMP);
87 
88 	return (error);
89 }
90 
91 int
92 linux_emul_convpath(td, path, pathseg, pbuf, cflag)
93 	struct thread	 *td;
94 	char		 *path;
95 	enum uio_seg	  pathseg;
96 	char		**pbuf;
97 	int		  cflag;
98 {
99 	struct nameidata	 nd;
100 	struct nameidata	 ndroot;
101 	int			 error;
102 	const char		*prefix;
103 	char			*ptr, *buf, *cp;
104 	size_t			 len, sz;
105 
106 	GIANT_REQUIRED;
107 
108 	buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
109 	*pbuf = buf;
110 
111 	prefix = linux_emul_path;
112 	for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
113 		continue;
114 	sz = MAXPATHLEN - (ptr - buf);
115 
116 	if (pathseg == UIO_SYSSPACE)
117 		error = copystr(path, ptr, sz, &len);
118 	else
119 		error = copyinstr(path, ptr, sz, &len);
120 
121 	if (error) {
122 		*pbuf = NULL;
123 		free(buf, M_TEMP);
124 		return error;
125 	}
126 
127 	if (*ptr != '/') {
128 		error = EINVAL;
129 		goto keeporig;
130 	}
131 
132 	/*
133 	 * We know that there is a / somewhere in this pathname.
134 	 * Search backwards for it, to find the file's parent dir
135 	 * to see if it exists in the alternate tree. If it does,
136 	 * and we want to create a file (cflag is set). We don't
137 	 * need to worry about the root comparison in this case.
138 	 */
139 
140 	if (cflag) {
141 		for (cp = &ptr[len] - 1; *cp != '/'; cp--);
142 		*cp = '\0';
143 
144 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
145 		error = namei(&nd);
146 		*cp = '/';
147 		if (error != 0)
148 			goto keeporig;
149 	}
150 	else {
151 		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
152 
153 		if ((error = namei(&nd)) != 0)
154 			goto keeporig;
155 
156 		/*
157 		 * We now compare the vnode of the linux_root to the one
158 		 * vnode asked. If they resolve to be the same, then we
159 		 * ignore the match so that the real root gets used.
160 		 * This avoids the problem of traversing "../.." to find the
161 		 * root directory and never finding it, because "/" resolves
162 		 * to the emulation root directory. This is expensive :-(
163 		 */
164 		NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path,
165 		       td);
166 
167 		if ((error = namei(&ndroot)) != 0) {
168 			/* Cannot happen! */
169 			NDFREE(&nd, NDF_ONLY_PNBUF);
170 			vrele(nd.ni_vp);
171 			goto keeporig;
172 		}
173 
174 		if (nd.ni_vp == ndroot.ni_vp) {
175 			error = ENOENT;
176 			goto bad;
177 		}
178 
179 	}
180 
181 	NDFREE(&nd, NDF_ONLY_PNBUF);
182 	vrele(nd.ni_vp);
183 	if (!cflag) {
184 		NDFREE(&ndroot, NDF_ONLY_PNBUF);
185 		vrele(ndroot.ni_vp);
186 	}
187 	return error;
188 
189 bad:
190 	NDFREE(&ndroot, NDF_ONLY_PNBUF);
191 	vrele(ndroot.ni_vp);
192 	NDFREE(&nd, NDF_ONLY_PNBUF);
193 	vrele(nd.ni_vp);
194 keeporig:
195 	/* Keep the original path; copy it back to the start of the buffer. */
196 	bcopy(ptr, buf, len);
197 	return error;
198 }
199 
200 void
201 linux_msg(const struct thread *td, const char *fmt, ...)
202 {
203 	va_list ap;
204 	struct proc *p;
205 
206 	p = td->td_proc;
207 	printf("linux: pid %d (%s): ", (int)p->p_pid, p->p_comm);
208 	va_start(ap, fmt);
209 	vprintf(fmt, ap);
210 	va_end(ap);
211 	printf("\n");
212 }
213